1. Field of the Invention
The present invention relates generally to an apparatus for use with aerobic treatment systems. More specifically, the invention relates to a liquid disinfectant dispenser for treating sewage wastewater prior to discharging effluent into the environment.
2. Description of the Related Art
Aerobic treatment systems treat wastewater using natural processes that require oxygen. Bacteria work to break down and digest the wastewater inside the aerobic treatment unit. Because these bacteria flourish in high-oxygen environments, aerobic treatment systems require air to be injected into the system to facilitate the breakdown of wastewater. Even after breakdown, however, the treated wastewater leaving the unit requires additional treatment or disinfection before being returned to the environment.
Most aerobic treatment systems include a main compartment called an aeration chamber in which injected air is mixed with wastewater. Because most home aerobic units are buried underground, the air is forced into the aeration chamber by an air compressor or mixed by liquid agitation. The forced air mixes with wastewater in the aeration chamber, and the oxygen supports the growth of aerobic bacteria that digests the solids in the wastewater.
Because the bacteria cannot digest all of the solids, the undigested solids eventually settle out as sludge. Many aerobic units include a secondary chamber called a settling chamber or holding chamber where excess solids can settle. Other designs allow the sludge to accumulate at the bottom of the tank. In aerobic units designed with a separate settling compartment, the sludge returns to the aeration chamber (either by gravity or by a pumping device). The sludge contains bacteria that also aid in the treatment process.
As the sewage separates into liquid and solid components, the liquid is collected into the separate holding chamber where it can be pumped back to the surface or into a leach field. Prior to discharge, however, the liquid must treated with chlorine or similar disinfector to produce an antiseptic output. Only after disinfecting can the liquid be safely discharged into the environment.
Until recently, the typical method of treating the wastewater within an aerobic system was to cause the wastewater to come into contact with chlorine tablets, but chlorine in tablet form has traditionally been more difficult and expensive to acquire in solid form vis-à-vis chlorine in liquid form, such as common household bleach. Accordingly, regulation of such systems has been relaxed to allow the increased use of liquid chlorine in aerobic treatment systems. Liquid chlorine has lower cost than chlorine in tablet form and is more readily available.
Several patents have addressed the use of liquid chlorine in such systems. U.S. Pat. No. 6,932,912 (the '912 patent), for example, provides a wastewater treatment system for residential septic systems wherein liquid chlorine is drawn into the storage tank to treat sewage effluent. A liquid chlorine supply canister is connected by a supply tube and venturi chamber to a recirculating pipe that discharges the liquid chlorine into a storage-mixing tank. As the effluent is discharged, some of the effluent is recirculated back into the storage-mixing tank to facilitate efficient mixing of the chlorine.
Similarly, U.S. Pat. No. 6,627,071 (the '071 patent) provides a chlorinator for these systems that is designed to discharge a uniform volume of disinfectant. A check valve separates a container from the disinfectant supply, and the check valve limits flow into the container during operation of the effluent pump. After the pumping cycle, the check valve opens to allow the container to refill with disinfectant.